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PRIMARY MEMORYPRIMARY MEMORY
OF COMPUTEROF COMPUTER
WELCOME TO MY PRESENTATION
Presenter
SYED HAMIDUR RAHMAN
ID:16161037
DEP OF PUBLIC ADMINISTRATION
BANGLADESH UNIVERSITY OF PROFESSIONALS
DEFINITION
 Primary storage, also known as main storage or memory,
is the area in a computer in which data is stored for quick
access by the computer's processor.
 The terms random access memory (RAM) and memory
are often as synonyms for primary or main storage.
Primary Memory also called main memory. Main memory
is directly or indirectly connected to the central processing
unit via a memory bus .The CPU continuously reads
instructions stored there and executes them as required.
Example:
1: Ram
2: Rom
3:Cache
Primary Memory has limited capacity and data is lost when
power is switched off. It is generally made up
semiconductor device.
Characteristics of Main /Primary Memory :
1:These are semiconductor.
2: It is known as main memory.
3: Usually volatile memory
4: Data is lost in case power is switched off.
5: It is working memory of the computer
Faster than secondary memories.
6:A computer cannot run without primary memory.
Function of Primary Memory:
RAM(Random Access Memory):
• The read & write m/y of a computer is called RAM.
• The users can write information into RAM and read
information from it.
• It possesses random access property.
• In this m/y can be accessed on a random manner.
• It is a volatile memory.
Types of RAM
1:SRAM
2:DRAM
3:SDRAM
4:DDR2 RAM
SRAM:Static Random Memory Access
The information need to be refreshed.
In this it retain stored information only as long as the
power supply is on.
SRAM stands for static RAM, which is so named
because it does not need the periodic refresh rates like
DRAM. Because of how SRAMs are designed, not
only are refresh rates unnecessary, but SRAM is much
faster than DRAM and much more capable of keeping
pace with modern processors.
DRAM(dynamic random
access memory:
Dynamic RAM (DRAM) is the types of memory chip used for
most of the main memory in a modern PC.
The main advantages of DRAM are that it is very dense,
meaning you can pack a lot of bits into a very small chip, and
it is inexpensive, which makes purchasing large amounts of
memory affordable.
Double data rate synchronous dynamic random-access
memory (DDR SDRAM) is a class of memory integrated
circuits used in computers.
The DDR SDRAM interface makes higher transfer rates
possible by more strict control of the timing of the electrical
data and clock signals
DDR SDRAM:
DDR2 SDRAM
DDR2 is simply a faster version of DDR memory: It achieves
higher throughput by using differential pairs of signal wires to
allow faster signaling without noise and interference problems.
DDR2 is still double data rate, just as with DDR, but the
modified signaling method enables higher clock speeds tobe
achieved with more immunity to noise and cross-talk between
the signals.
ROM(Read only Memory):
Read-only memory (ROM) is a type of non-volatile memory
used in computers and other electronic devices. Data stored in
ROM can only be modified slowly, with difficulty, or not at
all,
so it is mainly used to store firmware (software that is
closely tied to specific hardware and unlikely to need
frequent updates) or application software in plug-in
cartridges.
Types of Rom:
There are different variations on the classic ROM
chips which were manufacturer produced and could
not change. The most common are:
1: PROM
2: EPROM
3: EEPROM
PROM(Programmable read-only memory):
A programmable read-only memory (PROM) or field
programmable read-only memory (FPROM) or one-time
programmable non-volatile memory (OTP NVM) is a form
of digital memory where the setting of each bit is locked by
a fuse or anti fuse.
It is one of the type of ROM (read-only memory). The
data in them is permanent and cannot be changed.
EPROM(Erasable programmable read-only
memory) :
An EPROM (rarely EROM), or erasable programmable
read-only memory, is a type of memory chip that retains its
data when its power supply is switched off.
Computer memory that can retrieve stored data after a
power supply has been turned off and back on is called
non-volatile.
EEPROM (Electrically Erasable Programmable
Read-Only Memory):
This type of ROM works in a similar way to Flash memory
in that it can its contents can be 'flashed' for erasure ad then
written to without having to remove the chip from its
environment.
EEPROMs are used to store a computer system's BIOS, and
can be updated without returning the unit to the factory.
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